[sensors] Add Generic Sensor platform unit tests.

device/generic_sensor/fake_platform_sensor.h

Index: device/generic_sensor/fake_platform_sensor.h
diff --git a/device/generic_sensor/fake_platform_sensor.h b/device/generic_sensor/fake_platform_sensor.h
new file mode 100644
index 0000000000000000000000000000000000000000..1f571fbb95830098d5056ca9075a5a8f9da31b6f
--- /dev/null
+++ b/device/generic_sensor/fake_platform_sensor.h
@@ -0,0 +1,47 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef DEVICE_GENERIC_SENSOR_FAKE_PLATFORM_SENSOR_H_
+#define DEVICE_GENERIC_SENSOR_FAKE_PLATFORM_SENSOR_H_
+
+#include "device/generic_sensor/platform_sensor.h"
+
+namespace device {
+
+class FakePlatformSensor : public PlatformSensor {
+ public:
+  FakePlatformSensor(mojom::SensorType type,
+                     mojo::ScopedSharedBufferMapping mapping,
+                     uint64_t buffer_size,
+                     PlatformSensorProvider* provider);
+
+  mojom::ReportingMode GetReportingMode() override;
+  PlatformSensorConfiguration GetDefaultConfiguration() override;
+
+  bool started() const { return started_; }
+
+  using PlatformSensor::NotifySensorReadingChanged;
+  using PlatformSensor::NotifySensorError;
+  using PlatformSensor::config_map;
+
+ protected:
+  ~FakePlatformSensor() override;
+  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
+  void StopSensor() override;
+  bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) override;
+
+ private:
+  static constexpr double kMaxFrequencyValueForTests = 50.0;
+
+  PlatformSensorConfiguration config_;
+
+  bool started_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakePlatformSensor);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_FAKE_PLATFORM_SENSOR_H